It is the long-range purpose of this project to understand the biological role and mechanisms regulating the nucleotides, cyclic AMP and cyclic GMP in Escherichia coli. The interests during the current year were: 1) to develop a system whereby the adenylate cyclase of E. coli could be studied in a manner that preserved its repression properties; 2) to study the interrelatedness of E. coli adenylate cyclase with carbohydrate transport systems; 3) to outline the profile of cyclic GMP accumulation during the life cycle of E. coli.